After the Tomsk campaign, we traveled to Yakutsk for the next leg of the campaign that came with new scientific objectives. Our team now included three members from Vrije Universiteit Amsterdam, two members from Woods Hole Research Center and one collaborator from the Institute of Biological Problems of the Cryolithic Zone from the Russian Academy of Sciences. Our destination was a burn scar from last year’s fire season near the small village of Yert, approximately 200 km West of Yakutsk and surrounded by larch forests, sometimes mixed with pine forests, growing on permafrost terrain. Approximately 20% of the boreal biome are dominated by deciduous larch forests, yet we do not really know how wildfires influence carbon stocks of these ecosystems. We aimed to fill parts of these knowledge and data gaps by collecting ground measurements to quantify the amount of carbon released during these fire events. This is also a formidable opportunity to see on site what these forests look like before studying it at larger scales from satellite data.
Our first task was to reach our camping site located within the burn scar of approximately 900 km2. On our way to the field site our local collaborator and driver showed us how the forests are honored in Yakutian culture. We made several stops along the road to worship the Bayanay spirit, the spirit of hunting, taiga, and its animals and birds, by leaving several presents on trees. Our local collaborators told us that these offers would bring good luck to our field campaign. Thus, of course we were very generous.
We had been told that locals from Yert were quite excited that an international team would visit their village. Indeed, when our team arrived at the village after a five-hour drive from Yakutsk we were kindly welcomed by the chief of the village with a cup of kumiz, local drink of fermented horse milk, and several local dishes. While having tea we talked more about the scientific goals of our campaign, and the local surroundings. They were also intrigued about the fact that our ‘Dutch’ team consisted of team members of French, German, Belgian, American and Russian nationalities. When we selected this little village as our access point to access the burn scar several months ago several thousand kilometres from here, in Amsterdam, using road maps and satellite images, we had no idea that this local community would be so welcoming and honored by our visit.
The first five days we sampled burned plots with gradients in fire severity, soil characteristics and vegetation composition. In each plot, we performed a wide range of measurement including soil sampling for carbon analysis, aboveground biomass and combustion estimates, active layer thickness measurements, tree cores for stand age estimates and post-fire tree seedling counts. Getting into these plots in such a remote area was quite challenging as we had to hike in dense bushes or waterlogged grasslands carrying all the equipment and freshly collected samples, and some days were unfortunately rainy. With these wet and cold conditions, the camp fire became an important place after the working days to dry clothes, but also to keep positive minds sharing tea and snacks together. It was worth facing these tough conditions as we made some interesting and unexpected observations. For example, we did not expect to find relatively young, approximately 50 to 60 years old stands, that were very dense and burned with high severity.
Waking up with rain showers in the morning of the fifth day of the campaign, we decided in a hurry to return to the village one day earlier than originally planned. More than working under rainy conditions, we were worried about the road that could become too muddy, even for our sturdy all-terrain van. We got indeed stuck multiple times on the muddy road back to the village, but thanks to a collective ‘pushing’ effort of the team and particularly to the amazing skills of our driver and ‘hero’ Dima, we safely made it out through 15 kilometres to the village after four hours on a muddy forest road. And this was supposed to be our rest day!
The work in the second week around this burn scar aimed at finding and sampling unburned sites along a forest road. These unburned plots were selected as ‘best’ matches of our burned plots by having similar forest compositions and landscape positions. The measurements in these ’control’ plots will allow us to estimate pre-fire carbon stocks, and thus act as a reference for comparison with our burned sites. While the comfort of staying in the village and sampling along the road may sound easier than our earlier camping experience, we ran into several unexpected mishaps. Our van suddenly broke down on a seemingly ‘easy’ part of forest road, and one team member had to recover from a muscle strain for two days. We quickly learned making a plan B… or even plan C. Luckily, we could rely on our local collaborator and driver, which were of a tremendous help throughout the campaign in addition to taking care of most of the logistics. They were very helpful in sharing knowledge on the ecosystems, but also cooked delicious meals. The jury is still out whether Dima’s soup or Roman’s pasta was the best meal.
We collected data in 24 sites which will enable us to better understand carbon emissions from fires in these larch ecosystems. This dataset will be completed with similar measurements that we will make in another burn scar on the opposite side of the Lena river North of Yakutsk in the upcoming ten days.
This field campaign is part of the ‘Fires pushing trees North’ project funded by the Netherlands Organisation for Scientific Research (NWO) and affiliated with NASA ABoVE.
This blog post was written by Clement Delcourt, PhD student at Vrije Universiteit Amsterdam, researching carbon emissions from boreal fires.
2019 is bound to become one of the largest fire years on record in the Arctic Circle, and especially in Siberia. How much carbon these fires release remains a challenging question. Very little ground data on fire emissions is available for Siberia and estimations are difficult since the main part of the emissions originates from organic soils, which is harder to retrieve from satellite imagery than emissions from aboveground biomass. Our research team from the Vrije Universiteit Amsterdam (the Netherlands), Woods Hole Research Center, Northern Arizona University (USA), Pyrenean Institute of Ecology (Spain), and the Siberian Branch of the Russian Academy of Sciences and Tomsk State University (Russia) are joining forces to better understand fire dynamics in Siberia.
After an adventurous three-hour drive, our field crew gathered with the local collaborators at Kajbasovo Research Station near Tomsk, in Russia. We aimed at finding old pine trees in burned and unburned sites, which we then core with tree borers to build tree-ring chronologies. Wildfires in this western part of the Siberian boreal forest usually don’t burn with high intensity allowing some resilient trees to survive multiple fire cycles. Thus, we aimed at using the chronologies to reconstruct the fire history of the area and to assess the response and recovery times of the ecosystem after fire events and other disturbances.
Little did we know that we would ourselves witness the severity of this year’s fire season. Except for the first day, we did not see a clear sky. From then on, the sun would only appear as a bright orange or blood red ball behind lots of smoke originating from wildfires in the Krasnoyarsk region hundreds of kilometers away. One good thing about this is that it dampened the heat, since we were already quite warmly dressed in our tick- and mosquito-proof clothing.
Mosquitoes and heat, however, were only small obstacles, as we set out with our borers to find trees older than 100 years. We really wanted trees from that age so that we can build sufficiently long chronologies. Even at the most remote places we were surprised to often see signs of human activity such as past logging, resin extraction or littering. One day we even saved a duckling out of a fisher net set up a good 4 hours bumpy drive away from the next village. Or sometimes we would simply not find old trees because of natural disturbances or growth restrictions. Eventually, we did manage to sample 12 sites with old trees with different fire severities and hydrologic characteristics. These will now be analysed further in the lab to extract and crossdate the tree rings.
Being in the field and having only very little time to sample can be an intense working experience, but there were many special little moments too. Our driver overcame every obstacle on the way to bring us to very remote places, and our cook took great care of us with plenty of delicious borscht, buckwheat and blinis (type of pancakes) and provided large amounts of water and kompot (sweet fruit beverage). And our evenings were spent at camp fires diving into local culture and connecting the people.
After ten exciting days in Tomsk we are now resting and recovering in Yakutsk for the weekend. We are using the time for some team building activities, and we are enjoying some solid hours of sleep. We went shopping for supplies for the second part of our field campaign, which will lead us to even more remote areas around the little villages of Ert and Batamay in the next four weeks. There, we will visit recently burned forests and measure the carbon losses due to fire events. In addition, we will take more tree chronologies to estimate the stand age, and count seedlings to see how forests recover after fires of different severities.
This field campaign is part of the ‘Fires pushing trees North’ project funded by the Netherlands Organisation for Scientific Research (NWO) and affiliated with NASA ABoVE. The Tomsk part of the campaign was funded by INTERACT.
This blog post was written by Rebecca Scholten, PhD student at Vrije Universiteit Amsterdam, researching arctic-boreal fire dynamics.
By Eric Lindstrom
Instruments ready for Lagrangian array deployment at the end of the rainbow.
What do Leonhard Euler (1707-1783) and Joseph-Louis Lagrange (1736-1813) have to do with SPURS-2? How do we have two experiments going on simultaneously honoring the work of these famous mathematicians?
Two frames of reference have taken their names from these 18th century mathematicians. In science, including oceanography, when we make measurements of fluid flows fixed in space, we watch properties such as temperature or salinity as currents carry them by our instruments. This is called an Eulerian frame of reference. However, sometimes we make measurements while following the flow, trying to tag a parcel of water and watch as it moves and changes over time. This water following perspective is called the Lagrangian frame of reference. For example if you watch a river flow past from the bank, you are using an Eulerian frame of reference. If you examine the river from a boat flowing with river, you would be making a Lagrangian observation of the river.
In SPURS-2 we use moorings and a fixed grid of stations to describe a patch of ocean as the water passes by. Moorings, stations, and satellites provide the Eulerian perspective over the year of SPURS-2. We use a variety of drifters, autonomous vehicles, and profilers (instruments embedded in the moving water parcels) to also build an extensive Lagrangian view of the ocean over the year. We use the Lady Amber over the course of the year to service and reset some of the Lagrangian experiment as those assets drift away from the study site. We use the Revelle to deploy the Eulerian array and to seed the ocean with the Lagrangian instruments to be tended at later times by Lady Amber. It really is two experiments united to understand the salinity patterns and movement of freshwater in the ocean!
Audrey Hasson driving the A-frame during mooring deployment.
During the Revelle voyage we are also planning a short-term (48-72 hour) Lagrangian experiment capture the processes by which rainwater mixes into the ocean. We will launch drifters specially designed to follow the surface current during a rain event and then follow them for day or two. We will sample the region around the drifters using the Revelle to further examine the changing temperature and salinity properties of the upper ocean. The Revelle will attempt to take several snapshots of the ocean conditions as the Lagrangian array disperses over a day.
Together our Lagrangian and Eulerian sensor arrays constitute a sensor web in the ocean. This sensor web captures ocean motion and salinity changes (particularly) on a wide range of time and space scales. This allows us to analyze processes that lead to changing surface salinity all the way from minutes to seasons and from millimeter size turbulence to major ocean currents. We cannot measure all things we would like all the time and in every place, so we have tuned our effort and sensor web design to provide enough information to estimate what we would like to know. We would like to know about the role of turbulent mixing at the surface; we would like to know the role of eddies in transport of freshwater; and we would like to know how the major equatorial currents impact the eastern tropical Pacific low salinity pool. Obtaining such knowledge of the ocean is ambitious and challenging. SPURS-2 is giving us a shot at providing some unprecedented new knowledge.
Andy Jessup, Chief Scientist on SPURS-2 R/V Revelle.
I would like to give a shout out to our chief scientist on the voyage, Andy Jessup, from the University of Washington Applied Physics Laboratory. Andy has demonstrated extreme patience and diligence to his duty to represent the many investigators working on diverse problems and scales in SPURS-2. He has a team from APL aboard with a complex set of measurements to execute. He balances the time devoted to his own science project and his duties as leader of all the projects represented on the ship. That is not easy and he has found a way to give everyone a voice.
I hope to devote some upcoming blog time to our able CTD crew from Scripps led by Janet Sprintall, the ocean currents in our region in general, and the interaction with the teams back home as seen through the eyes of Audrey Hasson.
Please feel free to send questions and comments on the blog. I’ll do my best to answer all fair questions!
By Eric Lindstrom
A representation of the SAC-D spacecraft, which carried the Aquarius instrument.
One of the most common questions I get (and the first comment to this blog) is “How do you measure ocean salinity from space?” During the SPURS-1 campaign in 2012 I wrote a blog post on this topic. Basically the story is one of building a very sensitive instrument (a radiometer) to detect subtle variations of L-band microwave emissions from the ocean. Aquarius, launched in June 2011 was designed specifically for that purpose. Unfortunately, the spacecraft on which the Aquarius instrument flew suffered an unrecoverable failure in spring of 2015. Fortunately for oceanography, NASA launched Soil Moisture Active-Passive mission (SMAP) in January 2015. SMAP uses similar technology (an L-band radiometer) to measure soil moisture. While SMAP is not as sensitive as Aquarius, NASA is successfully producing a salinity product from this mission’s data.
The satellite missions detect only the salinity at the surface of the ocean. This tells us much about the exchanges of water with the atmosphere once we learn how to interpret the signals. The SPURS expeditions are all about learning how the surface salinity of the ocean changes so we can use the global surface salinity maps from space to diagnose matters of the water cycle over the ocean.
The European Space Agency also launched the Soil Moisture and Ocean Salinity mission (SMOS). It uses a different technology (a synthetic aperture antenna array) to make the measurements, but also provides a salinity product we use daily. Audrey Hasson from the French space agency is aboard R/V Revelle and helping us bring all the space data (salinity, temperature, winds, sea height, waves) to the ship to guide our daily operations.
Audrey Hasson, from the French space agency, aboard the R/V Revelle.
Most of the oceanographic work on this voyage is focused on measuring and understanding the variations of salinity in the top 10 meters (~30 feet) of the ocean. Here, in one of the rainier spots on the planet, rainwater freshens the surface ocean. The degree of freshening was not really appreciated until we saw the surface salinity from space. Measurements from ships and buoys usually miss sampling the upper few meters of the ocean because it is technically difficult to make those measurements. Taking full advantage of Aquarius and SMOS surface salinity observations has required a scientific revolution in measurement of salinity in the top 10 meters of the ocean.
Getting back to shipboard life, I am happy to report that all the minor cases of seasickness are abating. Those that suffered from it are now smiling and eating. No serious cases of seasickness occurred at all, so my guess is that all the first-timers will return to sea in future!
Deploying the Surface Salinity Profiler.
Also, today was the first trial deployment of one of our key instruments, the Surface Salinity Profiler (SSP), from University of Washington Applied Physics Lab. It’s a salinity measurement “laboratory on a sailboard” that can be towed at outboard of the ship. The instrument can measure salinity simultaneously and continuously at several shallow depths away from the ship’s influence and wake. The trial was devoted to the mechanics of deployment and recovery and the dynamics of towing the system. You will hear much more about SSP as the voyage progresses.
Recovering the Surface Salinity Profiler.
Winds dropped over night and whitecaps have largely disappeared. The sky is broken clouds with an occasional very light rain shower. Air temperature is 80°F. So overall, the weather conditions for test deployments off the ship are much better today!
By Eric Lindstrom
Our wave gliders, ready for action.
Fieldwork in physical oceanography, like many sciences, requires enormous preparation followed by a shorter very intensive period of action. SPURS-2 is no exception. The work over the next six weeks has been in the planning and staging for several years. Now, all the gear and scientists have reached the ship and we are on our way to completing all of our the carefully laid plans.
It is tempting to express the mood aboard the R/V Revelle as a great sense of anticipation. From discussion around the ship, it seems like no one has seen a voyage with these many sensors and equipment installed aboard this ship. There seem to be instruments mounted everywhere from bow to stern! And, of course, the scientists and technicians are deeply interested in what each sensor will tell them and what kind of scientific discoveries will emerge. These instruments are designed to see the delicate slow dance between the ocean and atmosphere around the ship over the coming weeks. Other gear will be deployed to continue the careful watch on ocean and atmosphere for the next year. All our time and investment is focused on understanding the aspects of this “slow dance” that involve water exchanges between ocean and atmosphere. In the atmosphere we will be looking at the characteristics of rainfall and evaporation at the sea surface. In the ocean we will be study the characteristics of the temperature and salinity patterns induced by the rain. These interactions are a newly accessible field of study resulting from the advent of satellite rainfall and salinity measurements and new shipboard tools for studying the upper few meters of the ocean.
One of the numerous meteorological masts installed on the R/V Revelle for SPURS-2.
All the scientific party on R/V Revelle likely feel some sense of adventure, since the precise nature of what we will see and discover is a matter of conjecture. We do know from the Aquarius satellite data that there is a large pool of relatively fresh water built up seasonally at the surface of the eastern tropical Pacific north of the equator. Oceanographers are curious as to how this pool is trapped in the region for part of the year and how it is seasonally released to the west. As physicists, we are tackling the problem by careful examination of the individual processes that bring the water into the ocean (rain), maintain the fresh pool in the ocean (dynamics), and subsequently release the water to the west or to the deep (dynamics and mixing). If we knew the answers, it wouldn’t be research. The unknown beckons! The combined feelings of curiosity and anticipation –and that our work may result in deeper understanding of nature–, just seem to make this feel like an adventure!
The chief scientist of SPURS-2, Andy Jessup, is ready for action too.
So here we are, all primed for discovery but with five days more to go before being where we really want to work. We are like kids in the back seat of the car asking “are we there yet?” Every piece of gear is at the ready and the teams are completing their training. We are doing dry runs to iron out the deployments of new devices that just have not seen that much action. In later entries, I’ll introduce you to the Sea Snake and the Surface Salinity Profiler and the Lighter-than-Air InfraRed System (LTAIRS), a balloon. These are very new ways of examining the air-sea interaction near the ship. They will be used in conjunction with many of our standard tools – drifters, wavegliders, and moorings, for example. We hope they will lead us to deeper insights about the water cycle at the ocean surface. I will give you a preliminary view of what is discovered during the week-long return voyage to Honolulu at the end of September. For now, we simply prepare for action!
